Re: BIG Joins

Jeff Evarts <jde_at_Unify.com> wrote:
}I`m curious... how many people out there know of a runtime environment
}where a "common" operation on a database involves a join of more than,
}say, 5 tables?
}
}It seems to me this is fairly rare, limited mostly to large reports
}that would get spooled off at EO[DWMY].
}
}Have YOU ever written one?

    Yes, if you count self-joins (see below).

}Was it a one-shot or something intended for repeated use?

    Runs several times a day.

}What was it for?

    Generate "/etc/group".

##      range of l1 is listpropmap
##      range of l2 is listpropmap
##      range of p1 is properties
##      range of p2 is properties
##      retrieve (
##          name        = list.#name,
##          lid         = list.#list_id,
##          gid         = l1.prop_value
##      ) where list.#is_active != 0
##          and list.#list_id = l1.#list_id
##          and l1.#prop_id = p1.#prop_id
##          and p1.#name = "gid"
##          and list.#list_id = l2.#list_id
##          and l2.#prop_id = p2.#prop_id
##          and p2.#name = "group" {
                /* ... */
##      }

John ``no Sucky Query Language for me'' Hascall

-- 
John Hascall                   ``An ill-chosen word is the fool's messenger.''
Systems Software Engineer
Project Vincent
Iowa State University Computation Center  +  Ames, IA  50011  +  515/294-9551